藏红花挥发油共有组分的气相色谱-质谱分析

本文采用气相色谱-质谱(GC-MS)法分析不同批次的藏红花挥发性成分,探讨同一产地不同批次藏红花挥发组分的成分与含量,并用峰面积归一化法确定各成分的相对含量,以其中的主要挥发组分作为考察指标,观察不同批次藏红花挥发组分的变化情况.初步鉴定出42种成分,且同一产地不同批次藏红花挥发性成分具有一定相似性.     

发酵香肠成熟前后挥发性成分的固相微萃取-GC-MS分析

采用固相微萃取—气相色谱—质谱联用分析技术对发酵香肠挥发性成分进行了定性分析和峰面积相对含量的测定：结果表明,发酵香肠在成熟前(发酵结束时)的主要挥发性风味物质的成分为乙酸、3—羟基—2—丁酮、2—丁酮、1—羟基—2—丙酮等;成熟香肠的风味成分主要为乙酸、3—羟基—2—丁酮、2—丁酮、酯类物质、挥发性酚、醛类以及少量的烯及含氮化合物等。发酵香肠的风味发育赋予了该产品典型的感官风格。     

黑胡椒根萜类化合物的分析

报道了用蒸馏 萃取法提取黑胡椒根中挥发性物质,测得黑胡椒根挥发油的质量分数为3.1%,用GC/MS法从黑胡椒根挥发油中分离并确定出28种化学成分。其中主要成分为萜类化合物,占总检出量的82.48%。     

LP-DOAS测量乙二醛时大气中干扰吸收的去除(英文)

针对利用长光程差分吸收光谱技术在实现对大气中乙二醛实时监测中,一些干扰结构(Xe灯结构,H2O、NO2和O4干扰吸收)对长光程差分吸收光谱技术的影响,讨论了乙二醛的光谱反演方法对干扰吸收的准确去除.针对Xe灯结构由于压力和多普勒展宽程度等的变化而引起的Xe灯结构的非线性变化,采用不同时刻的参考灯谱通过光谱插值的方式准确去除,其去除误差引起的剩余结构可降低到比乙二醛的最低理论检测限低3倍;针对H2O的非线性吸收以及特征吸收结构随柱浓度的不同而变化的特点,采用较高和较低浓度H2O吸收光谱插值的方法准确去除了严重干扰乙二醛准确反演的H2O的吸收结构,其去除误差引起的剩余结构可降低到比乙二醛的最低理论检测限低10倍;另外,对于在此波段存在干扰的NO2和O4的吸收结构也实现了准确地去除.干扰结构的准确去除使DOAS对乙二醛的监测实现了较低的实际检测限(0.15ppbv)和较低的测量误差(～10%).最后,在广州郊区对实际大气进行了实际监测,其浓度范围在低于检测限到1.66ppbv之间,与文献报道的浓度范围和变化趋势十分吻合.     

加速溶剂萃取法提取烟叶挥发性成分条件的优化

以色谱指纹图谱信息量为指标,用正己烷为萃取剂,采用均匀设计法优化了萃取时间、萃取温度和泵入萃取池溶剂量占池体积百分数3个因素对加速溶剂萃取法萃取烟叶挥发性成分的影响,由此提出了一快速测定烟叶挥发性成分的方法。所得萃取液用气相色谱-质谱联用(GC-MS)检测后,用NIST质谱数据库检索进行定性分析,共鉴定出44种化学组分,占挥发油总量的88.87%,所得结果能为烟叶化学成分的研究提供有利的科学依据。     

薤白挥发油成分的超临界CO2萃取及GC-MS分析

采取超临界CO2萃取和水蒸气蒸馏两种方法提取薤白中的挥发油,比较了两种提取方法得到的挥发油的理化性质,并利用GC-MS对它们进行了定性、定量分析。两种方法的主要提取物均为含硫化合物,但超临界CO2萃取法得到的含硫化合物的数量和质量都高于水蒸气蒸馏法得到的提取物。采用水蒸气蒸馏法提取8 h得到的萃取率为1.72%。通过设计的超临界CO2萃取的正交实验,得到了最佳萃取工艺条件为:压力25 MPa,温度40℃,CO2流量为25L/h。最佳萃取时间为120 min,萃取率为4.41%,是水蒸气蒸馏法萃取率的2.8倍。实验结果表明,超临界CO2萃取法简单易行,可以较快速、有效地提取薤白中的挥发油。     

顶空液相微萃取测定溶剂型涂料中挥发性有机物

应用顶空液相微萃取法对溶剂型涂料中的挥发性有机物(VOC)进行分离富集,直接进样气相色谱法分析。对萃取溶剂进行了筛选,并研究了平衡温度、溶剂体积、萃取时间等影响因素对萃取效率的影响。在优化的条件下,苯、甲苯、二甲苯、三氯乙烯和四氯乙烯的检出限分别为0.25、0.25、0.75、1.25和1.75μg/L。进行了方法的准确度和精密度试验,平均回收率为94.14%~119.33%,相对标准偏差为2.9%~18.9%。     

山豆根和北豆根挥发性成分的对比分析

采用GC-MS对山豆根和北豆根的挥发性化学成分进行了分析。通过谱图检索和解析,从山豆根中确定了35种挥发性成分,从北豆根中确定了31种。其中北豆根中的化合物类型较多,含氮化合物和含氧杂环化合物明显较北豆根多。两种中草药中量最多的都是脂肪酸,但山豆根为十八碳二烯酸、十六碳酸和六碳酸;北豆根为十三碳烯酸。     

Effects of ultrasound treatment on muscle structure,volatile compounds,and small molecule metabolites of salted Culter alburnus fish

This study investigated the effects of ultrasound treatment on the quality of salted Culter alburnus fish. The results showed that with the increasing ultrasound power, the structural degradation of muscle fibers was intensified, and the conformation of myofibrillar protein was significantly changed. The high-power ultrasound treatment group (300 W) had relatively higher thiobarbiturate reactive substance content (0.37 mg malondialdehyde eq/kg) and peroxidation value (0.63 mmol/kg). A total of 66 volatile compounds were identified with obvious differences among groups. The 200 W ultrasound group exhibited fewer fishy substances (Hexanal, 1-Pentene-3-ol, and 1-Octane-3-ol). Compared with control group, ultrasound groups (200, 300 W) contained more umami taste-related amino peptides such as γ-Glu-Met, γ-Glu-Ala, and Asn-pro. In the ultrasound treatment group, L-isoleucine and L-methionine, which may be used as flavor precursors, were significantly down-regulated, while carbohydrates and its metabolites were up-regulated. Amino acid, carbohydrate, and FA (fatty acyls) metabolism products in salted fish were enriched by ultrasound treatment, and those products might ultimately be related to the taste and flavor of salted fish.     

Recent studies on advance spectroscopic techniques for the identification of microorganisms: A review

The continuous development of resistance to antibiotic drugs by microorganisms causes high mortality and morbidity. Pathogens with distinct features and biochemical abilities make them destructive to human health. Therefore, early identification of the pathogen is of substantial importance for quick ailments and healthcare outcomes. Several phenotype methods are used for the identification and resistance determination but most of the conventional procedures are time-consuming, costly, and give qualitative results. Recently, great focus has been made on the utilization of advanced techniques for microbial identification. This review is focused on the research studies performed in the last five years for the identification of microorganisms particularly, bacteria using advanced spectroscopic techniques including mass spectrometry (MS), infrared (IR) spectroscopy, Raman spectroscopy (RS), and nuclear magnetic resonance (NMR) spectroscopy. Among all the techniques, MS techniques, particularly MALDI-TOF/MS have been widely utilized for microbial identification. A total of 44 bacteria i.e., 6 Staphylococcus spp., 3 Enterococcus spp., 6 Bacillus spp., 4 Streptococcus spp., 6 Salmonella spp., and one from each genus including Escherichia, Acinetobacter, Pseudomonas, Proteus, Clostridioides, Candida, Brucella, Burkholderia, Francisella, Yersinia, Moraxella, Vibrio, Shigella, Serratia, Citrobacter, and Haemophilus (spp.) were discussed in the review for their identification using the above-mentioned techniques. Among all the identified microorganisms, 21% of studies have been conducted for the identification of E. coli, 14% for S. aureus followed by 37% for other microorganisms.